Folks

I thinking about rebarreling a Sharps 45-120 (34” octagon Douglas barrel with 1 in 20 twist) to a 45-70.  My questions are:  What twist rate and barrel length to you recommend and why?  I plan to shoot most smokeless powder in the 200 to 300 yard range but might venture into the Holy Black and try 600 to 1000 yards.

I may be asking way too much of the caliper and barrel but might as well go for the moon!!!


Your opinions would be welcomed.

Thanks

Tennessee Snuffy

my 45-70's  17 twist Kreiger was A phenominal shooter with 530 Money bullets. Then I built a  RKS 17 gain twist. Also A great Quigley gun........throated out for the 540? Saeco ,held 72 gr.  3F    shot 50 fps under a 45-90  alot cheaper for brass......

Faster twists are necessary to use longer and heavier bullets.

We have transitioned to going to tighter twists to shoot longer heavier bullets further distances. 

Shorter bullets in faster twist rifles spin faster and the overspinning may affect accuracy.

We use gyroscopic stability factor calculators such as the Don Miller formula to assess the proper match of bullet length and twist to ensure we have adequate spin to stabilize the bullet or to find the point where accuracy may be affected by too much overspinning of the bullet.

I still wonder how the Creedmoor shooters in 1874 were able to shoot a 530 gr. bullet in their .44-77 BN, or .44-90 BN accurately at 1000 yds. using the slow twist rates most people today refuse to use, and think wont work with those heavy bullets?
I shoot a 1:16" twist in my .40-65 Roller with a 415 gr. Snover bullet, but I also shoot an original Ballard Pacific with a .40-85 Ballard chamber, and a 1:20" twist rate using the same bullet at the same velocity. Both are very accurate rifles with great bores, and the Ballard might have a slight edge with it's slower twist rate.
I'm just not convinced that you have to have the fast twist barrels that the formulas suggest to shoot accurately with heavier bullets.